Does the Earth have more than one Moon?

Technically, Earth has only one Moon. The one we can see and have called by various names over the ages: Luna in Italian, Latin, and Spanish, Lune in French, Mond in German, and Selene in Greek, Cynthia is another poetic name, though rare, for the Moon personified as a goddess.

(The Moon Landing)

But here is the interesting thing. Over millions of years, the number of moons has varied.

The Earth formed around 4.5 billion years ago, and at that time it had no moons at all. Then, the story goes, this proto-Earth was struck by a Mars-sized object called Theia. The blast from this huge crash threw out a lot of debris into orbit around Earth. This debris coalesced to form our Moon.

This is the “real” Moon. But on and off astronomers have also found other natural satellites orbiting the Earth, which can be considered temporary, and/ or “mini-moons”.

The temporary satellites are those captured by Earth’s gravity. They orbit our planet for some time, before breaking away and escaping into space. For example, there was a satellite called 2006 RH120. This is a tiny near-Earth asteroid with a diameter of approximately 2–3 meters. Generally, it orbits the Sun but comes close to the Earth–Moon system around every twenty years. When it does, it can temporarily enter Earth’s orbit. Most recently, it was in Earth orbit from July 2006 to July 2007, during which time it was never more than 0.0116 AU (1.74 million km) from Earth.

There was also 2020 CD3, another similar small satellite that entered the Earth’s orbit, escaping in March 2020 after orbiting the Earth for three years.

While the Earth orbits the Sun, it is not alone on its celestial journey. There are other objects that share its cosmic neighbourhood, known as Trojans. Two such Trojans are 2010 TK7 and 2020 XL5. They occupy unique positions in space called Lagrange points, where the gravitational forces of the Earth and the Sun achieve a delicate equilibrium. These points are gravitationally stable, allowing the Trojans to follow Earth’s orbital path around the Sun.

A large amount of dust particles also collects in the Lagrange points. These are known as the Kordylewski clouds and scientists have known about them since 1961, when Polish astronomer Kazimierz Kordylewski, after whom they are named observed, them for the first time. They had been hypothesised since the 1950s.

Snow Moon Feb 26 2021. Photo: 360onhistory

In a study conducted in 2018 Hungarian astronomers and physicists studying the Lagrange points L4 and L5 of the Earth and Moon said they had confirmed the existance of two Earth orbiting moons. The team was able to capture images of two mysterious clouds 250,000 miles away (approximately the same distance as the moon). They called these translucent clouds of dust that orbit along with our moon, “Ghost moons”.

(Moon Landing Conspiracy Theories Part 1)

There are other companions of Earth as well. One is a sort of a “quasi-moon”, which is not really orbiting the Earth but instead is orbiting the Sun. This asteroid is called 2003 YN107 and its orbit around the Sun is almost identical to that of Earth’s. However, the path of 2003 YN107 is kind of like a corkscrew, which makes it seem like it is orbiting the Earth. It was a “quasi-satellite” of Earth from 1996 to 2006 due to this wonky path.

In 2016, another quasi-satellite was identified. This intriguing object orbits the Sun while remaining closely tethered to Earth, caught in its gravitational influence. It is believed to have been accompanying us for nearly a century and is expected to continue doing so for several more years.

There are other close objects as well that come close to our planet but then head away in the opposite direction around the Sun, meeting the Earth on the other side. They trace out horshoe like paths known as horseshoe orbits. An object discovered in 2002 called 2002 AA29 follows such as horseshoe path relative to Earth, but will not be a quasi-satellite again for 500 years.

(Moon Landing Conspiracey Theories Part 2)

Asteroid Cruithne (a Q-type, Aten asteroid in orbit around the Sun in 1:1 orbital resonance with Earth) also sometimes visits our planet and loops around it.

Funnily enough, the large number of artificial satellites orbiting the Earth are also sometimes mistaken for potential moons. For example, astronomers were very excited about observing a new moon in 2015, which later turned out to be the Gaia space telescope.

So, there you go. Earth really does have only one moon, but over time it has had other companions. Most likely, it will have many more in the millennia to come.

A New Moon Visits Earth in September 2024

[BONUS] Here is the first photo ever taken of the real Moon on March 23, 1840.

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